9812vram

PCM middle plug Pin 31 is +5V to VSS.

Gov pressure sensing wire is pin 29, middle plug.

Gov pressure sensor gets it's 12v supply from trans control relay. PCM controls this relay by grounding Trans Relay (or called Auto Shutdown Relay on your truck, located in power distribution center) at PCM middle plug, pin 30, pink wire. Sensor shares a common ground that ends at PCM pin 4 which I believe is the plug on the engine side of PCM.

freightrain

Idleing at startup (cold) i got 5.2 v at pin 31 (orange wire) and .7v at pin 29 (green with white tracer) I'm going to go drive it, get up to temp and check again. IT only goes into limp mode when the trans is warm, seems to work fine up shift and down while cold. Maybe it is a gps gone bad?

9812vram

Ya, it sounds like it, pretty common issue too. I can't tell you the voltages you should see at pin 29 at the moment. I can't remember off hand exactly what it's supposed to be now and my manual is at home. I'll post the specs tonight but in the mean time maybe someone else has the info at hand??

freightrain

I drove the truck and same thing, once trans. warmed up, would go into limp mode once it hit 3rd gear. So I drove down to radio shack and bought a 5 pack of 100 ohm resistors for $1.50. I soldered one into the orange wire (pin 31) and appears to have fixed my problem! It dropped the sensor supply from 5.23 volts to 4.2. Before i did this fix the voltage coming from the sensor was .7v at idle in park, 4.6v at idle in drive. I wasn't able to hook my multimeter and monitor while driving, but it appears the line pressure just is much higher than stock while driving down the road and goes into limp mode the resistor trick is working so far. Thanks for everyone's help and input!!!

9812vram

Hey freightrain,
I got home and took a look at the diagrams. I guess I told you some stuff wrong. Should have made sure before I blabbed my mouth off on here. Sorry guys. I'll clarify:

Pin 31, orange wire feeds +5v to the VSS, but yes, it also feeds the gov pressure sensor.
For anyone else viewing, the resistor trick also works on pin 29, green/white wire (gov pressure signal wire).
It's the solenoids that are fed 12v from the Auto Shutdown Relay (Trans Control Relay), not the sensor.

As far as Governor Pressures and Voltages, the specs are as follows:
Speed.....Pressure.....Signal Voltage.....Control Voltage
0mph.........0psi...............66v............... ....8.30v
10mph.......8psi...............90v................ ...8.60v
20mph......38psi..............1.10v............... ..9.45v
30mph......60psi..............1.45v............... ..9.80v
40mph......65psi..............1.80v............... 10.30v
50mph......68psi..............2.15v............... 10.80v
60mph......70psi..............2.95v............... 13.80v

Signal voltages taken from gov pressure signal wire pin 29, green/white tracer, middle plug
Control Voltages taken from gov solenoid control wire pin 8, violet/white tracer, middle plug

Pressures will vary slightly depending on tire size and axle ratios.
It's a Dodge, wire colors could be different too !

freightrain

thats some good info. Is that for stock 47re? I talked to ATS and they said line pressure in drive at idle with foot on brake should be 60-70 psi. the voltage at pin 29 in drive at idle was 4.6v, so i can imagine what the pressures are when driving, much higher than stock.

9812vram

Yep, those are for a bone stock 47re. Pressures/voltages will vary accordingly but you should still be able to figure out roughly what pressures and voltages you should see with the ATS valvebody.
Remember: Line pressure and Governor Pressure are different. Line pressure is clutch apply pressure and governor pressure is used for shifting and is directly proportional to wheel speed.
Governor pressure must overcome line pressure and the force of the shift spring in order to hit the next gear. So no matter how high your line pressure is, at idle in drive with foot on brake there should be zero governor pressure. I'm not sure why you're seeing the voltages you are at pin 29....The .7v you saw at idle in park should be the same at idle in gear according to the chart. But as long as she shifts and don't throw codes, hammer down!

freightrain

Yeah, that is a good question, i definitely will investigate further once i acquire a gauge that i can monitor the pressures as i drive. Its possible there is a valve body issue?

I know when i bought the truck it was in limp mode because some jack-**** had removed the trans. shift relay and he was driving it like that for who knows how long and thought the slow starts were because overdrive was out saying the valve body was bad. I've heard that can burn up a transmission in a hurry, so maybe there is another issue causing high governor pressure? Other than possibly a faulty gps, what would cause pressure at the gps in drive at idle? Is there a test port to hook up a gauge to see the actual governor pressure? I am still going to do what ATS recommended and check line pressure and start from there.

9812vram

Ya, it could be internal leakage in the valve body I suppose... although I'd still be leaning more towards the gov pressure sensor or maybe the solenoid itself.

This should help with the pressure diagnostics:

Stinson Pilot

Where is the Governor Solenoid located?
I'm have the same problem with a stock tranny.

Thanks

9812vram

Here ya go:

freightrain

Thanks, i will get under there and check it out whenever i get a chance!